lone star 2013 conference training session

Advanced-Ruby.md

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+**Presenter:** Anthony Lewis
+
+## Bio
+This is a training session @ 2013 [Lone Star Ruby Conference](http://www.lonestarruby.org/2013/)
+
+## Abstract
+This training covers the following topics:
+
+  * Ruby Object model
+  * Modules/ Mixing
+  * Metaprogramming
+
+## Summary
+
+  * In Ruby, everything is an object, you can define methods on class level and instance level.
+  * `inlcude` is for instance methods and `extend` is for class methods, you can also use `include` to do `extend`
+  * learn how to use `prepend` to effeciently do Fiboniacci method
+  * `method missing` is powerful and dangerous (see example)
+
+## Memorable Quotes
+
+  * "The wifi really sucks..."
+  * "Usually people don't do live coding as a presentation, but I'd like to try to get my hands dirty."
+
+## Notes
+
+### Ruby Object Model
+  `send` : `calling a method is also sending a message`
+
+    Person.new.send :greet
+
+Singleton Class (Eigenclass): a singleton method is a method defined on an instance
+
+    superman = Person.new("Clark")
+    def superman.fly
+      puts "Up, up, and high"
+    end
+    superman.singleton_class
+    > #<Class:#<Person:0x007fa0eb03c6c0>>
+
+### Modules/Mixins
+  include: instance methods, extend class methods.
+  Prep a module: include module methods before methods defined in the class
+
+    module Memoize
+      def calc(n)
+        @@memo || = {}
+        @@memo[n] || = super
+      end
+    end
+
+    class Fib
+      # without prepend, it's not fast.
+      def calc(n)
+        return n if n < 2
+        return calc(n-1) + calc(n-2)
+      end
+    end
+
+### Metaprogramming
+  `class_eval`: creates instance method, evaulate a code string (type is String) as if it were typed directly into the class definition
+
+      > p.name
+      > NoMethodError: undefined method 'name'
+
+      class Class
+        def get_attr(attr)
+          self.class_eval "
+            def #{attr}
+              @#{attr}
+            end
+          "
+        end
+      end
+
+      class Person
+        get_attr :name
+      end
+
+  `define_method`: create a method at runtime
+
+      class Person
+        define_method :punch do |arg|
+          "Ouch!"*arg
+        end
+      end
+
+  `method_missing`: invoked when a method is not found
+      class method_missing(method, *args)
+        # do something
+      end
+
+### Rails attributes, Rails dynmaic finders
+
+      def method_missing(meth, *args)
+        if metho.to_s =~ /^find_by_(.+)$/
+          find_by_attributes(attr, *args)
+        else
+          super
+        end
+      end
+
+      def find_by_attributes(attr, *args)
+        conditions = Hash[attr.map {|a| [a, args[attr.index(a)]]}]
+        where(condition, args)
+      end
+
+### Method decoractors / class decorators
+
+      module TrackMethod
+        def track(meth)
+          self.class_eval do
+            alias_method "old_#{meth}", meth
+            define_mthod meth do |*args|
+              puts "logging #{meth} with #{args.join(',')}"
+              self.send "old_#{meth}", args
+            end
+          end
+        end
+      end
+
+      # in the class where you want to use the tracking
+      class Person
+        extend TrackMethod
+
+        track :greeting
+
+        def greeting
+          # something
+        end
+      end
+    ````
+### Show me only the instance_methods defined
+      > p = Person.new
+      > p.class.instance.instance_methods(false)
+
+###Use Ruby Set
+    require 'set'
+
+    class User
+      def initialize
+        @features = Set.new
+      end
+
+      def method_missing(meth, *args)
+        if meth.to_s =~ /^can_(.*)\?$/
+          @features.include? $1.to_s
+        elsif meth.to_s =~ /^can_(.*)$/
+          @features << $1.to_s
+        else
+          super
+        end
+      end
+    end
+
+## Discussion
+
+Define new instance method as we go..
+
+    # define a new method inside that class
+    def method_missing(meth, *args)
+      if meth.to_s =~ /^can_(.*)\?$/
+        self.class.class_eval do
+          define_method meth.to_sym do
+            @features.include? $1.to_s
+          end
+        end
+      elsif meth.to_s =~ /^can_(.*)$/
+        self.class.class_eval do
+          define_meth meth.to_sym do
+            @features << $1.to_s
+          end
+        end
+      else
+        super
+      end
+    end
+
+## External Links
+* [Some related website](http://www.lonestarruby.org/2013/)

Marshall-Shen.md

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 Twitter: MarshallShen
-GitHub: fshen
+GitHub: marshallshen